1. Field
A linear compressor is disclosed herein.
2. Background
FIG. 1 shows a configuration of a linear compressor according to the related art. Referring to FIG. 1, a linear compressor 1 according to the related art includes a cylinder 3 provided in an interior of a shell 2, a piston 4 that linearly reciprocates in the interior of the cylinder 3, and a motor assembly 20 that provides a driving force to the piston 4.
The shell 2 includes a suction unit or inlet 2a, through which a refrigerant is introduced, and a discharge unit or outlet 2b, through which a refrigerant compressed in the interior of the cylinder 3 is discharged. A refrigerant suctioned through the suction unit 2a flows into an interior of the piston 4 through a suction muffler 30. As a refrigerant passes through the suction muffler 30, noise may be reduced.
In the inside of the cylinder 3, a compression space P in which a refrigerant is compressed by the piston 4, is formed. A suction hole, through which a refrigerant is introduced into the compression space P, is formed in the piston 4, and a suction valve 5 configured to selectively open the suction hole is provided in or at one side of the suction hole.
A discharge valve assembly for discharging the refrigerant compressed in the compression space P is provided in or at one side of the compression space P. That is, the compression space P may be understood as a space formed between a one end side of the piston 4 and the discharge valve assembly.
A discharge cover 7 configured to form a discharge space of a refrigerant, a discharge valve 6 opened when a pressure of the compression space P is a discharge pressure or more and introducing a refrigerant into the discharge space, and a valve spring 8 provided between the discharge valve 6 and the discharge cover 7, and providing elastic force in an axial direction are included in the discharge valve assembly. The term “axial direction” may be understood as a direction in which the piston 4 reciprocates, that is, a transverse direction in FIG. 1.
A frame 10 is further included in the linear compressor 1. The frame 10 is configured to fix the cylinder 3, configured integrally with the cylinder 3 or may be fastened by a separate fastening member.
Stators 21 and 22 and a permanent magnet 23 are included in the motor assembly 20. An outer stator 21 fixed to the frame 10 and arranged to surround the cylinder 3, and an inner stator 22 spaced apart to or at an inner side of the outer stator 21 are included in the stators 21 and 22. The permanent magnet 23 may be located in a space between the outer stator 21 and the inner stator 22. The permanent magnet 23 may be linearly reciprocated by a mutual electromagnetic force between the outer stator 21 and the inner stator 22.
The permanent magnet 23 may be coupled to the piston 4 by a connection member 24. The connection member 24 may be extended to the permanent magnet 23 from one end of the piston 4. As the permanent magnet 23 is linearly moved, the piston 4 may be linearly reciprocated in the axial direction with the permanent magnet 23.
A coil winding body and a stator core are included in the outer stator 21. A bobbin and a coil wound in a circumferential direction of the bobbin are included in the coil winding body. The stator core is configured so that a plurality of laminations is stacked in the circumferential direction, and may be arranged to surround the coil winding body.
When a current is applied to the motor assembly 20, the current flows in the coil, a flux is formed around the coil by the current flowing in the coil and the flux flows along the outer stator 21 and the inner stator 22 while forming a closed circuit. As the flux flowing along the outer stator 21 and the inner stator 22 and the flux of the permanent magnet 23 are interacting, a force for moving the permanent magnet 23 may be generated.
A stator cover 29 is provided in or at one side of the outer stator 21. One end of the outer stator 21 is supported by the frame 10 and the other end may be supported by the stator cover 29.
The inner stator 22 is fixed to an outer periphery of the cylinder 3. The inner stator 22 is configured so that a plurality of laminations is stacked at an outer side of the cylinder 3 in the circumferential direction.
A supporter 25 that supports the piston 4 and a back cover 26 that extends from the piston 4 toward the suction unit 2a are further included in the linear compressor 1. The back cover 26 may be arranged to cover at least a portion of the suction muffler 30.
A plurality of springs 27 and 28 to which an inherent number of vibrations is adjusted, is included in the linear compressor 1, so that the piston 4 may able to perform a resonant motion. A first spring 27 supported between the supporter 25 and the stator cover 29 and a second spring 28 supported between the supporter 25 and the back cover 26 are included in the plurality of springs 27 and 28. A plurality of first springs 27 may be provided at both sides of the cylinder 3 or the piston 4, and a plurality of second springs 28 may be provided at the cylinder 3 or a rear of the piston 4.
With respect to such a related art linear compressor, the present Applicant has filed and registered an application (hereinafter referred to as a “prior application”), Korean Patent Registration No. KR 10-1454550, entitled “linear compressor”, which is hereby incorporated by reference. In order to increase a capacity of a compressor, it is necessary to increase a drive frequency of the compressor or a bore of a cylinder. If, in consideration of a size or operation reliability of a compressor, the drive frequency and the bore of the cylinder should be fixed to a specific value, in order to increase the capacity of the compressor, it is necessary to increase a stroke of a piston (or stroke).
However, according to the related art linear compressor, due to interference of a piston and adjacent components, a stator forming a motor, and a limited length of a permanent magnet, there is a problem that there are limitations to increasing the stroke of the piston to a set level or higher. After all, there is a problem that the capacity of a linear compressor cannot be improved.